Should the fontanelles be examined in a 17‑month‑old child during a routine well‑child visit?

Fontanelle Examination in a 17-Month-Old Child

Yes, you should examine the fontanelles in a 17-month-old child during routine well-child visits, as the anterior fontanelle typically remains open at this age and provides important clinical information about intracranial pressure, hydration status, and developmental abnormalities. 1, 2

Timing of Normal Fontanelle Closure

• The anterior fontanelle has a median closure time of 13.8 months, with a normal range extending from 4 to 26 months of age 3, 4
• At 17 months, many children will still have a palpable anterior fontanelle, making examination both feasible and clinically relevant 3
• The fontanelle should be assessed while the infant is upright and calm, appearing flat and level with the skull 2

Critical Clinical Information from Fontanelle Examination

Normal Findings

• A flat fontanelle (level with the skull) when the child is upright and calm indicates normal intracranial pressure 2

Pathological Findings Requiring Immediate Evaluation

A bulging or full anterior fontanelle is always abnormal and indicates increased intracranial pressure from conditions such as meningitis, intracranial hemorrhage, or hydrocephalus 2, 5

• In infants with bulging fontanelles, clinically significant abnormal findings on neuroimaging occur in 36% of cases 5
• Brain edema from infection is the most common pathological finding 5
• A sunken fontanelle typically indicates dehydration and requires fluid assessment 3

High-Risk Indicators Requiring Urgent Neuroimaging

• Febrile children younger than 2 months with a bulging fontanelle (88% have clinically significant abnormal neuroimaging findings) 5
• Any child with a bulging fontanelle AND abnormal neurological examination findings 5
• Presence of altered mental status, neck stiffness, seizures, or other abnormal neurological signs alongside fontanelle abnormalities 2

Assessment of Delayed Closure

If the fontanelle remains open beyond expected closure time at 17 months, evaluate for underlying conditions:

• Hypothyroidism, Down syndrome, and increased intracranial pressure are the most common causes of delayed closure 1, 3
• Achondroplasia and rickets are additional considerations for delayed closure beyond 24 months 1, 3
• However, persistent open fontanelles can be normal outliers once pathological conditions are excluded 4

Practical Examination Approach

• Palpate the fontanelle with the child sitting upright and calm to accurately assess for bulging or depression 2
• Measure the fontanelle size if it appears unusually large (normal average is 2.1 cm at birth) 3
• Always correlate fontanelle findings with overall clinical presentation, including vital signs, mental status, and neurological examination 2
• If abnormalities are detected, ultrasound through the open fontanelle is the preferred initial imaging modality as it avoids radiation exposure 2

Common Pitfall to Avoid

Do not dismiss a bulging fontanelle in a febrile infant as simply due to fever or crying—while most causes are self-limiting, 36% have clinically significant intracranial pathology requiring intervention 5, 6. However, the routine practice of performing lumbar puncture solely based on bulging fontanelle in well-appearing febrile infants should be reconsidered, as bacterial meningitis is rare (0.3%) in this presentation 6.